JP4243134B2 - Metal cylinder and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal cylindrical body used for high-pressure piping through which high-pressure fuel hydrogen gas or natural gas serving as fuel for power generation is passed, for example, in automobiles, houses, transportation machines, and the like, and a method for manufacturing the same.
[0002]
[Prior art]
As a metal cylindrical body, an electric resistance welded tube is widely used in which a metal plate is roll-formed to form a cylindrical shape, and a butt portion thereof is high-frequency welded.
[0003]
By the way, since the strength of the welded portion is reduced due to the heat effect of the electric resistance welded tube, there is a risk of fatigue failure due to stress concentration in the welded portion. Is currently not approved for use.
[0004]
Therefore, it is considered to use a mandrel extrusion tube, a porthole extrusion tube, or the like as the pressure piping.
[0005]
However, the mandrel extruded tube is prone to uneven thickness and has a problem that a large diameter and / or long tube cannot be obtained. Moreover, there exists a problem that the thing of complicated cross-sectional shape cannot be obtained. On the other hand, the porthole extrusion tube can solve such problems, but has the following problems. That is, as is well known, the porthole extrusion tube is manufactured by once separating the metal material flowing from the billet at the port portion of the porthole die and then welding the separated metal material again at the chamber portion. A plurality of pipe constituent parts are welded to each other by a plurality of welds extending over the entire length, but mechanical properties such as strength and elongation and corrosion resistance are inferior to the pipe constituent parts in the welded parts, and used for pressure piping. In some cases, the welded portion may be broken due to stress concentration.
[0006]
By the way, it is considered that if the welded portion of the porthole extruded tube is modified, it can be used for pressure piping. As a method for improving the corrosion resistance of the welded portion of the porthole extruded tube, it is known to subject the billet used for extrusion to various heat treatments (see, for example, Patent Document 1).
[0007]
[Patent Document 1]
JP-A-11-172387 (Claims)
[0008]
[Problems to be solved by the invention]
However, the method for improving the mechanical properties of the welded portion is not yet known, and the current situation is that the use of the porthole extruded tube for the pressure piping has been neglected.
[0009]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a metal cylindrical body that is long and large, and has excellent pressure resistance, and a method for manufacturing the same.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises the following aspects.
[0011]
1) It consists of a porthole extruded tube in which a plurality of pipe constituent parts are welded to each other by a plurality of welded portions over the entire length, and a reforming process is performed on the metal that is the base material of the porthole extruded tube in all the welded portions, Metal cylinder with fine crystal grains.
[0012]
2) The metal cylindrical body according to 1) above, wherein the modification treatment of the porthole extruded tube is performed by friction stirring using a probe of a friction stir welding tool.
[0013]
3) The metal cylindrical body according to 1) or 2) above, wherein a reinforcing partition is fixedly provided in the porthole extruded tube so as to partition the inside of the porthole extruded tube into a plurality of spaces.
[0014]
4) The metal cylindrical body according to 3) above, wherein the reinforcing partition is friction stir welded to the porthole extruded tube at at least two welds.
[0015]
5) The metal cylindrical body according to 3) above, wherein the reinforcing partition is integrally provided in a tube constituent portion of the porthole extruded tube.
[0016]
6) A fuel hydrogen gas cylinder, a fuel cell, and a pressure pipe for sending fuel hydrogen gas from the fuel hydrogen gas cylinder to the fuel cell, and the pressure pipe is a metal cylinder described in any one of 1) to 5) above A fuel cell system consisting of a body.
[0017]
7) A fuel cell vehicle equipped with the fuel cell system described in 6) above.
[0018]
8) A cogeneration system comprising the fuel cell system according to 6) above.
[0019]
9) A natural gas supply system comprising a natural gas cylinder and a pressure pipe for sending out natural gas from the natural gas cylinder, wherein the pressure pipe is made of a metal cylindrical body described in any one of 1) to 5) above.
[0020]
10) A cogeneration system comprising the natural gas supply system according to 9) above, a generator, and a generator drive device, and a pressure pipe for sending natural gas from the natural gas cylinder to the generator drive device.
[0021]
11) A natural gas vehicle comprising the natural gas supply system according to 9) above and an engine using natural gas as fuel, and a pressure pipe for sending natural gas from the natural gas cylinder to the engine.
[0022]
12) An oxygen gas supply system comprising an oxygen gas cylinder and a pressure pipe for sending oxygen gas from the oxygen gas cylinder, wherein the pressure pipe is made of a metal cylindrical body described in any one of 1) to 5) above.
[0023]
13) Place the probe of the friction stir welding tool outside on the welded part of the porthole extruded pipe where the pipe parts are welded together by the welded parts over the entire length so as to straddle the pipe parts on both sides of the welded part. Then, the porthole extrusion tube and the probe are moved relative to each other in the length direction of the porthole extrusion tube to frictionally stir the metal used as the base material of the porthole extrusion tube to refine the crystal grains. A method for producing a metal cylindrical body characterized by comprising:
[0024]
14) The distance between the tip of the probe embedded in the porthole extrusion tube and the inner peripheral surface of the porthole extrusion tube is 0.1 mm or more and 1/2 or less of the wall thickness of the tube wall. A method for producing a metal cylindrical body.
[0025]
15) The method for producing a metal cylindrical body according to the above 13) or 14), wherein the metal that becomes the base material of the porthole extrusion tube is frictionally stirred at the welded portion of the porthole extrusion tube immediately after extrusion coming out of the extruder.
[0026]
16) In the porthole extrusion tube, a reinforcing partition is placed so that the inside is divided into a plurality of spaces, and when the metal that becomes the base material of the porthole extrusion tube is friction-stirred in at least two welds, the probe Is embedded up to the reinforcing partition, and the reinforcing partition is friction stir welded to the porthole extrusion tube.
[0027]
17) The method for producing a metal cylindrical body according to any one of the above 13) to 15), wherein the reinforcing partition is integrally extruded over at least two pipe constituent parts of the porthole extruded pipe.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same part and the same thing through all drawings, and the overlapping description is abbreviate | omitted.
[0029]
In the following description, the term “aluminum” includes aluminum alloys in addition to pure aluminum.
[0030]
Embodiment 1
This embodiment is shown in FIGS.
[0031]
FIG. 1 shows a metal cylindrical body of Embodiment 1, and FIGS. 2 and 3 show a manufacturing method thereof.
[0032]
In FIG. 1, a metal cylindrical body (1) is a port having a circular cross section in which a plurality of, in this case, four pipe constituent parts (2b) are welded to each other by a plurality of, for example, four welding parts (2a) over the entire length. It consists of a hole extrusion tube (2), and each welded portion (2a) is subjected to a modification process on the metal that becomes the base material of the porthole extruded tube (2), and includes a belt-shaped portion having a predetermined width including each welded portion (2a). The crystal grains are made finer. The reforming part is indicated by (3).
[0033]
The porthole extruded tube (2) is made of, for example, any one of JIS A2000 alloy, JIS A5000 alloy, JIS A6000 alloy, and JIS A7000 alloy.
[0034]
The reforming process is performed by friction stir using a probe of a friction stir welding tool.
[0035]
Note that the cross-sectional shape of the porthole extruded tube (2) is not limited to a circle, but an ellipse (not limited to a mathematically defined ellipse, including a shape close to an ellipse, such as an oval), and other It may be irregular.
[0036]
Next, the manufacturing method of a metal cylinder (1) is demonstrated with reference to FIG. 2 and FIG.
[0037]
First, the porthole extruder (5) is used to extrude a porthole extrusion tube (2) in which a plurality of pipe constituent parts (2b) are welded to each other by a plurality of welded portions (2a) extending over the entire length. Also, on the outside of the outlet of the extruder (5), the same number of friction stir tools (6) as the welded part (2a) of the porthole extruded tube (2) are placed at a position corresponding to the welded part (2a). Place it in. The friction stir welding tool (6) includes a cylindrical rotor (7) in which a small-diameter portion (7a) is integrally formed coaxially with a tapered portion at a tip portion, and a small-diameter portion of the rotor (7) ( The end surface of 7a) is provided with a pin-like probe (8) which is integrally formed coaxially with the small diameter portion (7a) and has a smaller diameter than the small diameter portion (7a) (see FIG. 3). The rotor (7) and the probe (8) are made of a material that is harder than the porthole extruded tube (2) and has heat resistance capable of withstanding frictional heat generated during joining.
[0038]
Then, once the extrusion of the porthole extrusion tube (2) is stopped and the friction stir welding tool (6) is rotated, the porthole extrusion tube (2) immediately after extrusion coming out of the extruder (5) The probe (8) is embedded from the outside so as to straddle the pipe components (2b) on both sides of the welded part (2a) at the end of the welded part (2a), and the small diameter part (7a) in the tool (6) And the probe (8) are pressed against the outer peripheral surface of the porthole extrusion tube (2) (see FIG. 3). At this time, the distance between the tip of the embedded probe (8) and the inner peripheral surface of the porthole extrusion tube (2) is preferably 0.1 mm or more and 1/2 or less of the wall thickness of the tube wall. . When this distance is less than 0.1 mm, a V-groove extending in the length direction is formed on the inner peripheral surface of the porthole extrusion tube (2) during stirring and mixing by the probe (8) described later, and sufficient pressure resistance May not be obtained. If the thickness of the tube wall exceeds 1/2, the thickness of the portion to be modified out of the entire wall thickness of the tube wall becomes thin, and mechanical properties such as the strength and elongation of the welded portion (2a) are reduced. There is a possibility that improvement is insufficient and sufficient pressure resistance cannot be obtained. Note that the temperature of the porthole extrusion tube (2) immediately after extrusion coming out of the extruder (5) remains at the hot working temperature. Further, by pressing the shoulder portion, it is possible to obtain a good stirring state by preventing the fluffing of the softened portion that may occur at the start of stirring and during the stirring described later, and a porthole extruded tube (2) Further, frictional heat is generated by sliding with the shoulder portion to promote softening of the contact portion between the probe (8) and the porthole extrusion tube (2) and the vicinity thereof, and the porthole extrusion tube ( Generation of irregularities such as burrs on the outer peripheral surface of 2) can be prevented.
[0039]
Next, by restarting the extrusion of the porthole extrusion tube (2), the probe (8) is welded by relatively moving the porthole extrusion tube (2) and the friction stir welding tool (6). The port hole push tube (2) is moved in the length direction along the portion (2a). Then, due to the frictional heat generated by the rotation of the probe (8) and the frictional heat generated by sliding between the porthole extrusion tube (2) and the shoulder, the welded portion (2a) and its vicinity (see FIG. 3). In the range indicated by the chain line A), the metal that is the base material of the porthole extruded tube (2) is softened, and the softened portion is agitated and mixed by receiving the rotational force of the probe (8). 8) After the plastic flow to fill the passage groove, the phenomenon of rapidly losing frictional heat and solidifying by cooling is repeated with the movement of the probe (8), so that the welded part (2a) and its vicinity The metal as the base material is mixed by friction stirring and reformed to refine crystal grains. In this way, the metal cylindrical body (1) is continuously manufactured.
[0040]
The metal cylindrical body (1) described above is manufactured by continuously extruding the porthole extrusion tube (2) by cutting it at predetermined lengths. Since a hole is formed at the position where the probe (8) is pulled out of the metal cylindrical body (1), the portion where this hole exists is excised. Further, when manufacturing the last metal cylindrical body (1), a contact member is placed at a position corresponding to the welded portion (2a) on the end face of the porthole extrusion tube (2) completely exiting from the extruder (5). If it is arranged and the probe (8) is moved to the contact member and then pulled out, the probe (8) pull-out hole does not occur in the metal cylindrical body (1).
[0041]
In the first embodiment, the probe (8) of the friction stir welding tool (6) is used to modify the welded portion (2a) of the porthole extruded tube (2) immediately after extrusion and at the hot working temperature. However, the present invention is not limited to this, and a modified treatment may be applied to the welded portion (2a) of the porthole extruded tube (2) after being extruded and cooled.
[0042]
Embodiment 2
This embodiment is shown in FIGS.
[0043]
FIG. 4 shows the metal cylindrical body of the second embodiment, and FIGS. 5 and 6 show a method for manufacturing the metal cylindrical body.
[0044]
As shown in FIG. 4, the metal cylindrical body (10) has a porthole extrusion tube (2) with a reinforcing partition (11) extending over its entire length, and the porthole extrusion tube (2) has a plurality of spaces. It is provided in a fixed shape so as to partition. The reinforcing partition (11) has the same number of welded portions (2a) extending radially from the center line of the porthole extruded tube (2), and here four partition walls (11a) are integrally provided. The cross-sectional shape here is a cross. The tip of the partition wall (11a) is friction stir welded to the porthole extrusion tube (2) at the welded portion (2a). The reinforcing partition (11) is made of, for example, any one of JIS A2000 alloy, JIS A5000 alloy, JIS A6000 alloy, and JIS A7000 alloy.
[0045]
Here, the porthole extruded tube (2) and the reinforcing partition (11) may be formed of the same material or may be formed of different materials.
[0046]
Note that the cross-sectional shape of the porthole extruded tube (2) is not limited to a circle, but an ellipse (not limited to a mathematically defined ellipse, including a shape close to an ellipse, such as an oval), and other It may be irregular.
[0047]
Moreover, in FIG. 4, the number of the partition walls (11a) of the reinforcing partition (11) is the same as the number of welded portions (2a) of the porthole extruded tube (2), and the partition walls in all the welded portions (2a) (11a) is joined to the porthole extrusion pipe (2), but is not limited to this, the number of partition walls (11a) if the interior of the trunk (2) can be divided into a plurality of spaces May be less than the number of welded portions (2a). In this case, the partition wall (11a) is joined to the porthole extrusion tube (5) at the welded portion (2a) at a position corresponding to the partition wall (11a) among all the welded portions (2a).
[0048]
Next, the manufacturing method of a metal cylinder (10) is demonstrated with reference to FIG. 5 and FIG.
[0049]
First, a porthole extruded tube (2) in which a plurality of tube components (2b) are welded to each other by a plurality of welds (2a) extending over the entire length is extruded and cut into a predetermined length. Further, the reinforcing partition (11) is extruded and cut into the same length as the cut porthole extruded tube (2).
[0050]
Next, inside the cut port hole extrusion tube (2), the cut reinforcing partition (11) is aligned, and the tip of each partition wall (11a) matches the welded portion (2a) of the port hole extrusion tube (2). Insert so that it comes to the position (see FIG. 5). At this time, the tip of the partition wall (11a) is brought into close contact with the inner peripheral surface of the porthole extrusion tube (2).
[0051]
Next, while rotating the friction stir welding tool (6), the end portion of the welded portion (2a) of the porthole extruded tube (2) straddles the pipe components (2b) on both sides of the welded portion (2a). The probe (8) is embedded from the outside, and the shoulder portion between the small diameter portion (7a) and the probe (8) in the tool (6) is pressed against the outer peripheral surface of the porthole extrusion tube (2). At this time, the tip of the probe (8) is embedded up to the partition wall (11a) of the reinforcing partition (11) (see FIG. 6). In addition, the effect | action by pressing the said shoulder part on the outer peripheral surface of a porthole extrusion pipe (2) is as having described in Embodiment 1. FIG.
[0052]
Next, by moving the port hole extrusion tube (2) and the friction stir welding tool (6) relative to each other, the probe (8) is moved along the welded portion (2a) to the length of the port hole extrusion tube (2). Move in the direction. Then, as in the case of the first embodiment, the base metal is friction stir-mixed at the welded portion (2a) of the porthole extruded tube (2) and its vicinity (indicated by the chain line B in FIG. 6), and the modified As a result, the crystal grains become finer. At the same time, the frictional heat generated by the rotation of the probe (8) softens the base metal at the tip of the partition wall (11a) (indicated by the chain line B in FIG. 6). The phenomenon that the softening part plastically flows so as to fill the probe (8) passage groove after receiving the rotational force of the probe (8), and then rapidly loses frictional heat and solidifies by cooling. By repeating with the movement of 8), the porthole extruded tube (2) and the partition wall (11a) are joined. In this way, a metal cylinder (10) is manufactured.
[0053]
In manufacturing the metal cylindrical body (10) described above, a contact member is disposed at a position corresponding to the welded portion (2a) on both end faces of the porthole extruded tube (2), and the probe (8) is attached. After embedding in one abutment member and modifying the weld (2a) and joining the partition wall (11a), the probe (8) is moved to the other abutment member and pulled out. A pull-out hole of the probe (8) is not generated in the cylindrical body (1). Here, the contact member for embedding the probe (8) is not necessarily required.
[0054]
Embodiment 3
This embodiment is shown in FIG.
[0055]
In FIG. 7, the porthole extruded tube (2) of the metal cylindrical body (15) of this embodiment has an elliptical cross section. The other structure is the same as that of the metal cylinder (10) of the second embodiment, and is manufactured by the same method as that of the metal cylinder (10) of the second embodiment.
[0056]
Embodiment 4
This embodiment is shown in FIG.
[0057]
In FIG. 8, the metal cylindrical body (20) of this embodiment includes a reinforcing partition (21) extending over the entire length of the porthole extruded tube (2), and a plurality of spaces in the porthole extruded tube (2). It is provided integrally so as to partition. The reinforcing partition (21) has a cross-shaped cross section, and is provided integrally with each tube component (2b) of the porthole extrusion tube (2) and extends toward the center line of the porthole extrusion tube (2). A plurality of partition walls (21a) are integrated on the center line. That is, the reinforcing partition (21) is integrally formed with the porthole extruded tube (2), and each partition wall (21a) is integrally formed with the tube component (2b), and the porthole extruded tube (2 ) On the center line. This weld is indicated by (22).
[0058]
Note that the cross-sectional shape of the porthole extruded tube (2) is not limited to a circle, but an ellipse (not limited to a mathematically defined ellipse, including a shape close to an ellipse, such as an oval), and other It may be irregular.
[0059]
The metal cylinder (20) is manufactured by the same method as the metal cylinder (1) of the first embodiment.
[0060]
The metal cylinders (1), (10), (15), and (20) of the first to fourth embodiments include a fuel hydrogen gas cylinder, a fuel cell, and a pressure pipe that sends the fuel hydrogen gas from the fuel hydrogen gas cylinder to the fuel cell. It is used as a pressure pipe in some fuel cell systems. Such a fuel cell system is mounted on a fuel cell vehicle or used for a cogeneration system.
[0061]
Further, the metal cylinders (1), (10), (15), and (20) are a natural gas supply system including a natural gas cylinder and a pressure pipe that sends out natural gas from the natural gas cylinder, a generator, and a generator driving device. Is used as a pressure pipe for sending natural gas from a natural gas cylinder to a generator drive device.
[0062]
Further, the metal cylinders (1), (10), (15), and (20) are a natural gas cylinder and a natural gas supply system that includes a pressure pipe that delivers natural gas from the natural gas cylinder, and an engine that uses natural gas as fuel. Is used as a pressure pipe for sending natural gas from a natural gas cylinder to an engine.
[0063]
Furthermore, the metal cylinders (1), (10), (15), and (20) are used as pressure pipes in an oxygen gas supply system that includes an oxygen gas cylinder and a pressure pipe that delivers oxygen gas from the oxygen gas cylinder.
[0064]
However, the use of the metal cylindrical body according to the present invention is not limited to the pressure pipe as described above.
[0065]
【The invention's effect】
According to the metal cylindrical body of 1) and 2) above, a plurality of pipe constituent parts are welded to each other by a plurality of welded portions extending over the entire length, and all of the welded parts of the porthole extruded pipes Since the metal as the base material is subjected to a modification treatment and the crystal grains are refined, mechanical properties such as strength and elongation of the welded portion and corrosion resistance are improved. Therefore, the pressure resistance of the metal cylindrical body is excellent, and even when used for a pressure pipe such as a pressure pipe through which high-pressure gas flows, destruction at the welded portion is prevented. Further, uneven thickness does not occur, and the length and size can be increased. Furthermore, the thing of complicated cross-sectional shape can be obtained.
[0066]
According to the metal cylinders of the above 3) to 5), the pressure resistance is further improved.
[0067]
According to the method for producing a metal cylinder of 13), the metal cylinders of 1) and 2) can be produced relatively easily.
[0068]
According to the method for producing a metal cylindrical body of 14), the pressure resistance of the produced metal cylindrical body is surely improved.
[0069]
According to the method for producing a metal cylindrical body of 15) above, the production speed is increased and the production efficiency is improved as compared with the case of using a porthole extruded tube whose temperature has been lowered to the cold working temperature. When a metal cylindrical body is manufactured by the method of 13) above using a porthole extruded tube whose temperature has been lowered to the cold working temperature, the porthole extrusion is performed at and near the welded portion by frictional heat generated by the rotation of the probe. This is because it takes time to soften the tube. Further, according to the method for producing a metal cylindrical body of 15) , the solution treatment after the production of the metal cylindrical body can be performed uniformly, and the mechanical properties are stabilized. When a metal cylindrical body is produced by the method of 13) above using a porthole extruded tube whose temperature has been lowered to the cold working temperature, the temperature of the porthole extruded tube is locally increased at and near the welded portion, There is a possibility that the solution treatment after the production of the metal cylindrical body becomes non-uniform. Furthermore, according to the method for producing a metal cylindrical body of 15) above, even if a welding failure occurs between tube constituent parts in the initial stage of extrusion of a porthole extruded tube, this welding failure is eliminated. can do.
[0070]
According to the method for producing a metal cylinder of 16), the metal cylinders of 3) and 4) can be produced relatively easily.
[0071]
According to the method for producing a metal cylinder of 17), the metal cylinders of 3) and 5) can be produced relatively easily.
[Brief description of the drawings]
FIG. 1 is a partial perspective view showing a metal cylindrical body according to Embodiment 1 of the present invention.
FIG. 2 is a partial perspective view showing the method for manufacturing the metal cylindrical body according to the first embodiment.
FIG. 3 is a partially enlarged cross-sectional view showing the method for manufacturing the metal cylindrical body according to the first embodiment.
FIG. 4 is a partial perspective view showing a metal cylindrical body according to Embodiment 2 of the present invention.
FIG. 5 is a partial perspective view showing the method for manufacturing the metal cylindrical body according to the second embodiment.
FIG. 6 is a partially enlarged cross-sectional view showing a method for manufacturing a metal cylindrical body according to the second embodiment.
FIG. 7 is a cross-sectional view showing a metal cylindrical body according to Embodiment 3 of the present invention.
FIG. 8 is a partial perspective view showing a metal cylindrical body according to Embodiment 4 of the present invention.
[Explanation of symbols]
(1) (10) (15) (20): Metal cylinder
(2): Porthole extrusion tube
(2a): Welded part
(2b): Pipe component
(3): reforming section
(5): Porthole extruder
(6): Friction stir welding tool
(8): Probe
(11) (21): Reinforcing partition
(11a) (21a): Partition wall

Claims (17)

It consists of a porthole extruded tube in which a plurality of tube constituent parts are welded together by a plurality of welded parts extending over the entire length, and the reforming treatment is applied to the metal that is the base material of the porthole extruded tube in all welded parts. Is a metal cylinder that has been refined. The metal cylindrical body according to claim 1, wherein the reforming treatment of the porthole extruded tube is performed by friction stirring using a probe of a friction stir welding tool. The metal cylindrical body according to claim 1 or 2, wherein a reinforcing partition is fixed in the porthole extruded tube so as to partition the inside of the porthole extruded tube into a plurality of spaces. The metal cylindrical body according to claim 3, wherein the reinforcing partition is friction stir welded to the porthole extruded tube at at least two welds. The metal cylindrical body according to claim 3, wherein the reinforcing partition is integrally provided in a tube constituent portion of the porthole extruded tube. A fuel hydrogen gas cylinder, a fuel cell, and a pressure pipe for sending fuel hydrogen gas from the fuel hydrogen gas cylinder to the fuel cell are provided, and the pressure pipe is made of a metal cylindrical body according to any one of claims 1 to 5. Fuel cell system. A fuel cell vehicle equipped with the fuel cell system according to claim 6. A cogeneration system comprising the fuel cell system according to claim 6. A natural gas supply system comprising a natural gas cylinder and a pressure pipe for sending out natural gas from the natural gas cylinder, wherein the pressure pipe is formed of a metal cylindrical body according to any one of claims 1 to 5. A cogeneration system comprising the natural gas supply system according to claim 9, a generator, and a generator driving device, wherein the pressure pipe is configured to send natural gas from the natural gas cylinder to the generator driving device. A natural gas vehicle comprising: the natural gas supply system according to claim 9; and an engine using natural gas as a fuel, and the pressure pipe is configured to send natural gas from the natural gas cylinder to the engine. An oxygen gas supply system comprising an oxygen gas cylinder and a pressure pipe for sending out oxygen gas from the oxygen gas cylinder, wherein the pressure pipe is formed of a metal cylindrical body according to any one of claims 1 to 5. The probe of the friction stir welding tool is embedded from the outside so as to straddle the tube components on both sides of the welded portion in the porthole extruded tube in which a plurality of tube components are welded to each other by a plurality of welds extending over the entire length. After entering, the porthole extrusion tube and the probe are moved relative to each other in the length direction of the porthole extrusion tube to frictionally stir the metal used as the base material of the porthole extrusion tube to refine the crystal grains. A method for producing a metal cylindrical body characterized by the above. 14. The metal cylinder according to claim 13, wherein the distance between the tip of the probe embedded in the porthole extrusion tube and the inner peripheral surface of the porthole extrusion tube is 0.1 mm or more and 1/2 or less of the wall thickness of the tube wall. A method of manufacturing a body. The method for producing a metal cylindrical body according to claim 13 or 14, wherein the metal that becomes the base material of the porthole extruded tube is frictionally stirred at the welded portion of the porthole extruded tube that has just come out of the extruder. A reinforcement partition is placed in the porthole extrusion tube to divide the interior into multiple spaces, and the probe is reinforced when the metal that becomes the base material of the porthole extrusion tube is frictionally stirred in at least two welds. The method for manufacturing a metal cylindrical body according to any one of claims 13 to 15, wherein the partition is embedded up to the partition and the reinforcing partition is friction stir welded to the porthole extruded tube. The manufacturing method of the metal cylindrical body in any one of Claims 13-15 which extrude-molds the reinforcement partition integrally over the at least 2 pipe | tube structural part of a porthole extrusion pipe.

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